Photodynamic therapy (PDT) has emerged as a promising modality for the treatment of various types of cancer. Many porphyrins and related compounds have the unique ability to localize in tumors and thus sensitize them to photoirradiation. The availability of the less expensive diode laser and photosensitizers that absorb light at higher wavelengths will facilitate deeper tissue penetration of the light and make PDT more efficient and practical. Among certain porphyrins and phthalocyanines, it has been shown that introduction of fluorine increased the solubility in various injectable solvents allowing for drug formulation in a wider selection of vehicles. In this project we plan to synthesize long wavelength fluorinated and nonfluorinated photosensitizers that will be examined as: (i) hydrophobic, water insoluble compounds, (ii) hydrophilic amphiphillic compounds slightly water soluble and (iii) completely water soluble compounds. The new photosensitizers that pass the screening criteria will be evaluated for their photosensitizing efficacy, photodynamic damage to the blood vessels in the tumor, and skin phototoxicity. This will additionally provide the opportunity to study the role of fluorine on the biological properties of the new photosensitizers. MS has been used in our research projects to characterize intermediates, as well as target molecules.